Deck 13: Electric Circuits

Question 1

A 12 ohm resistor and a 24 ohm resistor are connected in parallel across a 6.0 V battery. The correct statement from the following is

A) the current is the same in each resistor.
B) the power dissipated is the same in each resistor.
C) the voltage difference between the ends of each resistor is the same.
D) the larger current is in the larger resistor.

Answer 1

the voltage difference between the ends of each resistor is the same.

Question 2

Three bulbs have power ratings for use on a 120 volt line: 60 watt, 100 watt and 150 watt. The one with the largest value of resistance has power rating

A) 150 W.
B) 100 W.
C) 60 W.
D) All have the same resistance.

Answer 2

60 W.

Question 3

In many ways, an electric circuit is like the plumbing system in your home. The voltage on an electric circuit corresponds to the ________ in a plumbing system.

A) trap
B) pressure
C) faucet or valve
D) drain

Answer 3

pressure

Question 4

An unmarked resistor is being used in a circuit. To determine its resistance by making voltage and current measurements, one should connect

A) the voltmeter and ammeter in parallel with the resistor.
B) the voltmeter and ammeter in series with the resistor.
C) the voltmeter in series with the resistor, and the ammeter in parallel with the resistor.
D) the voltmeter in parallel with the resistor, and the ammeter in series with the resistor.

Question 5

A 1.5 V flashlight battery, a 10 ohm resistor, and a flash?light lamp are available. How should the lamp be connected in a circuit so that it would glow the brightest?

A) Connect it in series with the resistor and battery so that the bulb is next to the positive terminal of the battery.
B) Connect it directly to the battery; don't use the resistor.
C) Connect it in parallel with the battery and the resistor.
D) Connect it in series with the resistor and battery so that the bulb is next to the negative terminal of the battery.

Question 6

The current (measured in amperes) in a circuit is

A) the total number of electrons in the circuit.
B) the amount of the total energy carried by 1 Coulomb of charge.
C) the amount of charge (measured in Coulombs) that passes a point (in the circuit) in 1 second.
D) never lethal if the current is due to positive charges.

Question 7

A 12 ohm resistor and a 24 ohm resistor are connected in series with a 6.0 V battery. The correct statement is

A) the voltage difference between the ends of each resistor is the same.
B) the power dissipated in each resistor is the same.
C) the current in each resistor is the same.
D) the smaller resistor carries the larger current.

Question 8

A certain kind of lightbulb carries 0.5 amperes of current when connected to a 120 volt AC circuit. What is its power rating?

A) 240 W
B) 100 W
C) 75 W
D) 60 W

Question 9

The resistance of a 50 watt bulb is ______ that of a 100 watt bulb, if both run on the same voltage.

A) one half
B) one fourth
C) four times
D) double

Question 10

One ampere is equivalent to

A) 1 J/s.
B) 1 C/s.
C) 1 N/C.
D) 1 V/m.
E) 1 ohm/volt.

Question 11

A student finds two ancient meters with numbered scales but no unit markings. He thinks that one is an ammeter and one is a voltmeter but doesn't know which is which. He measures the resistance of each, finding that meter A has a resistance of 5000 ohms and meter B has a resistance of 0.10 ohm. He can conclude that

A) B is the voltmeter and A is the ammeter.
B) A is the voltmeter and B is the ammeter.
C) A is the voltmeter but B cannot be a useful meter.
D) B is the voltmeter but A cannot be a useful meter.
E) neither can be a useful meter.

Question 12

A household circuit rated at 120 volts is protected by a fuse rated at 10 amps. What is the maximum number of 100 watt light bulbs which can be lit simultaneously in parallel in this circuit without blowing the fuse?

A) 4
B) 6
C) 12
D) 20
E) 24

Question 13

A 40 watt fluorescent bulb is rated for use in a 120 volt line. During a brownout the actual voltage drops to 102 V. The actual power dissipated in the bulb under these conditions is

A) 0.283 W.
B) 28.9 W.
C) 30.0 W.
D) 47.1 W.

Question 14

Two identical lightbulbs are installed in two sockets connected in parallel and power is then applied to the combination so that both bulbs light. If one of the bulbs is then removed from its socket, the other one will

A) get brighter.
B) get dimmer.
C) remain equally bright.
D) go out.
Power supply :
Series connection:
Parallel connection:

Question 15

The voltage drop across a resistor is 4.0 V for a current of 1.0 A in the resistor. What is the current that will produce a voltage drop of 8.0 V across the resistor?

A) 0.33 A
B) 1 A
C) 2 A
D) 0.50 A

Question 16

A flashlight bulb typically has a small metallic button at one end, and this button is surrounded by ceramic material. The chief purpose of the ceramic material is to

A) provide a conducting path to the filament.
B) shut the filament off if the current gets too high.
C) provide extra mass at the bottom of the bulb.
D) insulate the metal button from the other contact point.

Question 17

What is the best way to ensure that a 40 watt bulb and a 60 watt bulb have the same voltage applied to them?

A) Connect the bulbs in series with the power supply.
B) Connect the bulbs in parallel with the power supply.
C) It can't be done: different wattage bulbs must always have different voltages.

Question 18

The resistance of a circuit element is a measure of

A) the amount of work that an electron can perform.
B) the ratio of the voltage difference between element ends to the current in the element.
C) the size of the circuit.
D) the total energy of the charges in the circuit element.

Question 19

An ohm is equal to which of these?

A) A volt.
B) A Coulomb per second.
C) An ampere per second.
D) A volt per ampere.

Question 20

What is the best way to ensure that a 40 watt bulb and a 60 watt bulb have the same current within them?

A) Connect the bulbs in series with the power supply.
B) Connect the bulbs in parallel with the power supply.
C) It can't be done: different wattage bulbs must always have different currents.

Question 21

A resistor R is connected across a battery of negligible internal resistance. If the resistance of R is doubled, the current in R will be __________.

Question 22

When you pay your electric bill, what are you paying for, exactly?

A) The electrical energy you used the previous month.
B) The voltage you used the previous month.
C) The electrical charge you used the previous month.
D) The electrical power you used the previous month.
E) None of these.

Question 23

If the resistance in a circuit using an ideal (no internal resistance) battery is increased, then

A) the current coming out of the battery does not change.
B) the voltage difference maintained by the battery does not change.
C) the power output of the battery does not change.
D) All of the choices are correct.

Question 24

An iPod battery is rated at 3.7 volts and operates its iPod and earbuds with a direct current of 865 milliamps. What is the power rating of this iPod?

A) 16 Watts
B) 234 Watts
C) 3.2 Watts
D) 3.7 Joules per second

Question 25

In the water flow analogy with an electric circuit the pressure in the fluid circuit is analogous to ______________ in the electric circuit.

Question 26

A person discovers that the 5 ampere fuse in his car's brake light circuit is blown. Not having a spare 5 ampere fuse available, he replaces it with a new 10 ampere fuse. What is likely to happen as he uses the brakes?

A) Nothing bad happens; everything works well for a long time.
B) The brake lights shine more dimly than before.
C) The circuit overheats and the brake lights do not work.
D) The fuse blows immediately.

Question 27

Which of these is an electronic instrument that can plot voltage as it varies with time?

A) An ammeter.
B) A galvanometer.
C) An electroscope.
D) An oscilloscope.

Question 28

Three identical resistors can be connected in any combination. It's not necessary to include all three in any given combination. The number of distinct values of resistance that can be made is

A) two or fewer.
B) three.
C) four.
D) five.
E) six or more.

Question 29

In a laptop computer, the power converter plugs into the wall's AC outlet and it plugs into the computer's DC power jack. The direct current is composed of

A) electrons moving in the wire.
B) protons moving through the wire.
C) both protons and electrons moving through the wire in the same direction.
D) exactly one half of the voltage of the AC that operates the power converter.

Question 30

A power rating printed on a lightbulb assumes a voltage of 120 V is applied to the bulb. If two 100 W bulbs are connected in series to a 120 V source,

A) no current will pass through the bulbs.
B) each bulb radiates 100 W.
C) each bulb radiates more than 100 W.
D) each bulb radiates less than 100 W.

Question 31

Toasters have wires in them that heat up to warm the items placed inside. For the toaster to work properly, these wires must

A) be connected to a very large voltage.
B) have less resistance than the power cord.
C) be connected to a tiny voltage.
D) have more resistance than the power cord.

Question 32

Resistors of 10 ohms, 20 ohms, and 30 ohms are connected in series with a battery. The 10 ohm resistor is closest to the positive terminal and the 30 ohm resistor is closest to the negative terminal. What happens as the current flows through this circuit?

A) The most current is consumed in the 10 ohm resistor, less in the 20 ohm resistor, and the least in the 30 ohm.
B) A little current is consumed in the 10 ohm resistor, more in the 20 ohm, and the most in the 30 ohm.
C) None of the resistors consume current.
D) The resistors each consume the same amount of current.

Question 33

The alternating current in wide use in homes in North America is 60 cycles per second, or 60 Hz. How many times per minute does this current reverse its direction of travel?

A) 60 times.
B) 120 times.
C) 3600 times.
D) 7200 times.
E) none of these.

Question 34

When a nerve cell fires in your big toe, it is an interaction of positive and negative ions in the membrane of the nerve cell. This membrane has structural similarities to

A) a point charge.
B) oppositely charged parallel plates.
C) a dipole.
D) a solid block of positive ions embedded with a few impurities in the form of negative ions.

Question 35

An electric iron uses 8.0 A of current and has a power rating of 1100 W. The resistance of the iron is

A) 0.0072 W.
B) 17 W.
C) 138 W.
D) 8800 W.

Question 36

An iPod uses 3.7 volts with direct current of 865 milliamps. What is the equivalent resistance of the entire iPod system?

A) 4.3 ohms
B) 1 ohm
C) 3200 ohms
D) 8.4 ohms

Question 37

A copper wire from a large spool is cut into two lengths to make extension cords, one 50 feet long and the other 75 feet long. Which of the following is true?

A) The shorter cord will dissipate more power.
B) The shorter cord will have a smaller voltage.
C) The longer cord will be able to carry more current.
D) The longer cord will have more resistance.

Question 38

Three different resistance lightbulbs are connected to a 120-V outlet. The most power will be consumed by the circuit when

A) the bulbs are in series.
B) the bulbs are in parallel.
C) the least resistive bulb is in parallel with a series of the other two.
D) the most resistive bulb is in parallel with a series of the other two.
E) The arrangement is unimportant because the voltage is the same in all cases.

Question 39

If you load up a circuit in your home with too many devices, like lightbulbs or stereos, in ____________, then you can overload the circuit and trip a circuit breaker or blow a fuse.

A) series
B) parallel
C) summer
D) duplicate
Fill in the Blank Questions

Question 40

You have exactly 4 resistors: one 3 $\Omega$ , one 4 $\Omega$ , one 5 $\Omega$ , and one 6 $\Omega$ . How can you combine these to make a 2 $\Omega$ resistor? (The symbol $\Omega$ stands for "ohm.")

A) Connect the 3 $\Omega$ resistor in series with the 5 $\Omega$ resistor.
B) Connect the 3 $\Omega$ resistor in parallel with the 6 $\Omega$ resistor.
C) Connect the 3 $\Omega$ resistor in parallel with the 4 $\Omega$ resistor.
D) Connect all four resistors in parallel with each other.
E) You can't make a 2 $\Omega$ resistor from the ones listed.

Question 41

A dry cell battery is no longer useful when its ___________________ (two words) becomes large.

Question 42

A resistor R is connected across a battery of negligible internal resistance. If the resistance of R is cut in half, the power dissipated in R will ______________ (indicate change, if any).

Question 43

A student finds three resistors in the lab: a two ohm, a five ohm, and a 10 ohm resistor. The smallest value of resistance that the student can make using any one or any combination of the three resistors is ____________ ohms.

Question 44

In a series circuit, the most power is dissipated where the resistance is __________.

Question 45

As the temperature of a wire increases, its ___________ also increases.

Question 46

In the water flow analogy with an electric circuit the flow meter in the fluid circuit is analogous to the ________________ in the electric circuit.

Question 47

A one ohm, a two ohm, and a three ohm resistor are connected in parallel in an electric circuit: The resistor dissipating the most power will be the ____________ ohm resistor.